a) Field of the Invention
The invention is directed to a fiber-optic arrangement for additive mixing of a plurality of light bundles, especially laser light bundles which are guided independent and separate from one another in individual light-conducting cores, wherein each of the cores has a light entry location and a light exit location.
b) Field of the Related Art
For the reproduction of image information, especially in the entertainment and information fields, image generation devices in which light effects or images are generated on the basis of the useful radiation of lasers are being used to an increasing extent. This applies to installations provided for use in the open air as well as in enclosed spaces. A first generation of laser televisions is being developed in which the picture is displayed with the use of laser radiation.
In the above-mentioned new applications of laser technology in which the useful radiation of a laser lies in the visible spectrum and average outputs of several watts are required, there is a need for new safety devices for the prevention of personal injury. A primary danger consists in direct exposure of persons to laser radiation either through inattention or when the laser beam is unintentionally pointed directly at a person, e.g., due to malfunction of the image generation device. Therefore, safety regulations require that the laser light which may be hazardous to health is guided in waveguides. Light waveguides for laser radiation are known in the art.
On the other hand, available radiation sources have not yet achieved the light output required for desirable picture quality, especially in the reproduction of images on large displays. However, the light waveguides known in the art are not suitable for increasing put, in particular for laser radiation.
DE-OS 28 53 800 describes a directional coupler for partial or complete coupling of a light radiated into the core of a light waveguide over to the core of a second light waveguide. The cores which are embedded in a medium having a smaller index of refraction than that of the cores extend along a coupling path parallel to one another so as to practically contact one another. Along the coupling path, which has a length of 1 to 2 cm, the light waveguides are fixed in separate holders which can be displaced relative to one another and a displacing device having a forward feed which can be preset for adaptation of a splitting ratio is arranged at the holders.
This involves a so-called surface coupler for signal splitting over the cladding surfaces of the fibers in question. The two cores of the fibers are fused together at the surface along their line of contact which is roughly one to two centimeters long. In this fused area, entering light passes from one fiber into the other. This arrangement is suitable for coupling radiation with different optical information, but not for adding radiation outputs.